U.S. patent application number 10/873653 was filed with the patent office on 2005-01-20 for outboard engine system.
Invention is credited to Fukuda, Yoshihiko, Tawa, Hiroki.
Application Number | 20050011475 10/873653 |
Document ID | / |
Family ID | 34055325 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050011475 |
Kind Code |
A1 |
Tawa, Hiroki ; et
al. |
January 20, 2005 |
Outboard engine system
Abstract
In an outboard engine system, a first opening communicating with
a cooling water discharge passage and a second opening
communicating with a cooling water supply passage are formed
adjacent to each other in an upper wall of a cooling water passage
forming member. A relief valve is provided in a first opening at a
position remote from a tilt shaft. The relief valve includes a
valve seat provided at the upper wall and facing downward. A valve
body is seated on the valve seat from below. Accordingly, any
cooling water staying in an upper portion of the relief valve leaks
through gaps between the valve seat and the valve body to be
discharged easily. When the outboard engine system is tilted upward
about the tilt shaft, the opening provided with the relief valve is
moved upward so that the cooling water is discharged smoothly
through the other opening.
Inventors: |
Tawa, Hiroki; (Saitama,
JP) ; Fukuda, Yoshihiko; (Saitama, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN
1050 CONNECTICUT AVENUE, N.W.
SUITE 400
WASHINGTON
DC
20036
US
|
Family ID: |
34055325 |
Appl. No.: |
10/873653 |
Filed: |
June 23, 2004 |
Current U.S.
Class: |
123/41.08 |
Current CPC
Class: |
F02B 1/04 20130101; F01P
2007/146 20130101; F02B 61/045 20130101; F01P 7/14 20130101; F01P
2025/04 20130101; F02B 2275/18 20130101; F02B 2075/1816 20130101;
F02B 2075/027 20130101; F02B 75/20 20130101; F01P 3/202
20130101 |
Class at
Publication: |
123/041.08 |
International
Class: |
F01P 007/14; F01P
001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2003 |
JP |
2003-180969 |
Claims
What is claimed is:
1. An outboard engine system in which cooling water is supplied
from a cooling water pump through a cooling water supply passage to
a water jacket provided around a combustion chamber of an engine,
wherein internal pressure of the cooling water supply passage is
regulated by a relief valve, wherein the relief valve comprises: a
valve seat having a flange portion mounted to a substantially
horizontal upper wall and a cylindrical seat portion protruding
downward from the flange portion; a valve body seated on the seat
portion of the valve seat from below; and a valve spring which
biases the valve body upward toward the valve seat.
2. An outboard engine system in which cooling water is supplied
from a cooling water pump through a cooling water supply passage to
a water jacket provided around a combustion chamber of an engine
tiltably mounted around a tilt shaft, the cooling water of the
cooling water supply passage being discharged through a relief
valve into a cooling water discharge passage, wherein a first
opening communicating with the cooling water discharge passage and
a second opening communicating with the cooling water supply
passage are formed adjacent to each other in an upper wall of a
cooling water passage forming member, wherein a pressure regulating
passage is formed by covering upper portions of the first and the
second openings with a cover member, wherein the relief valve is
provided in one of the first and the second openings, and wherein
the other opening of the first and second openings is disposed
closer to a tilt shaft than the opening provided with the relief
valve.
3. The outboard engine system according to claim 2, wherein at
least a part of the relief valve is housed inside the cover member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an outboard engine system
wherein a relief valve is provided at an intermediate portion in a
cooling water supply passage to supply cooling water from a cooling
water pump to a water jacket.
[0003] 2. Description of the Related Art
[0004] In a conventional outboard engine system, cooling water used
to cool an engine is taken in through a cooling water intake port
provided at a gear case and supplied by a cooling water pump to a
water jacket surrounding a combustion chamber. During this process,
the pressure of the cooling water supplied to the water jacket is
regulated by a relief valve. The outboard engine systems disclosed
by Japanese Utility Model Application Laid-Open Nos. 50-127028 and
50-127728 include relief valves wherein a valve body is seated from
above into a valve seat, which is disposed in a horizontal
direction and protrudes upward.
[0005] The relief valve is closed when the engine of the outboard
engine system stops and when the engine operates at a low speed.
The relief valve opens when the engine operates at a high speed to
restrict the upper limit value of the pressure of the cooling water
being supplied to the water jacket. When the engine stops, the
relief valve closes, the cooling water in the cooling water
discharge passage on the downstream side from the relief valve is
discharged as is, and the cooling water in the cooling water supply
passage on the upstream side reversely flows through a gap in the
impeller of the cooling pump that has been stopped and is
discharged.
[0006] In the relief valve of the above-described conventional
outboard engine systems, the valve seat protrudes upward so the
valve body is seated from above. Therefore; when the engine stops
and the relief valve closes, it has been observed that cooling
water stays in a recessed portion surrounding the valve seat.
[0007] Further, because particular attention is not paid to the
disposition of the cooling water supply passage and the cooling
water discharge passage, which are connected to the relief valve,
the cooling water simply stays in the vicinity of the relief valve
when the outboard engine system is tilted upward to be landed after
the engine stops. Likewise, because salt is deposited in the
vicinity of the relief valve, the valve body has to be frequently
cleaned, resulting in additional and troublesome maintenance
work.
SUMMARY OF THE INVENTION
[0008] The present invention has been achieved in view of the
aforementioned circumstances. Accordingly, it is an aspect of the
present invention to ensure that cooling water does not remain in
the vicinity of the relief valve when the engine of the outboard
engine system stops.
[0009] In order to achieve the above-described aspect, according to
a first feature of the present invention, there is provided an
outboard engine system in which cooling water is supplied from a
cooling water pump through a cooling water supply passage to a
water jacket provided around a combustion chamber of an engine.
Internal pressure of the cooling water supply passage is regulated
by a relief valve, which includes a valve seat having a flange
portion mounted to a substantially horizontal upper wall and a
cylindrical seat portion protruding downward from the flange
portion. A valve body is capable of being seated on the seat
portion of the valve seat from below. The valve seat also has a
valve spring, which biases the valve body upward toward the valve
seat.
[0010] With the first feature, the relief valve of the outboard
engine system is constructed so that the valve body is biased from
below by the valve spring upward toward the valve seat provided at
the substantially horizontal upper wall. Therefore, any cooling
water remaining in the upper portion of the relief valve, which
closes when the engine stops, leaks through small gaps between the
valve seat and the valve body. In the valve seat of the relief
valve, the cylindrical seat portion protrudes downward from the
flange portion mounted to the upper wall. Therefore, it is ensured
that the water has difficulty staying between the flange portion
and the seat portion compared to the valve seat in the conventional
outboard engine systems wherein the cylindrical seat portion
protrudes upward from the flange portion.
[0011] According to a second feature of the present invention,
there is provided an outboard engine system in which cooling water
is supplied from a cooling water pump through a cooling water
supply passage to a water jacket disposed around a combustion
chamber of an engine tiltably mounted around a tilt shaft. The
cooling water of the cooling water supply passage is discharged
through a relief valve into a cooling water discharge passage,
wherein a first opening, communicating with the cooling water
discharge passage, and a second opening, communicating with the
cooling water supply passage, are formed adjacent to each other in
an upper wall of a cooling water passage forming member. A pressure
regulating passage is formed by covering upper portions of the
first and the second openings with a cover member. The relief valve
is provided in one of the first and the second openings, wherein
the other opening is disposed at a position closer to a tilt shaft
than the one opening having the relief valve.
[0012] With the second feature, the pressure regulating passage is
formed by covering the upper portions of the adjacently formed
first and second openings with the cover member. The relief valve
is provided in one of the first and the second openings, wherein
the other opening is disposed at a position closer to the tilt
shaft than the opening having the relief valve. Therefore, when the
outboard engine system is tilted upward around the tilt shaft in a
state in which the cooling water stays in the upper portion of the
relief valve, which has been closed as the engine stops, the
opening having the relief valve is moved upward and the opening not
having the relief valve is moved downward. Accordingly, the cooling
water is smoothly discharged through the opening not having the
relief valve and effectively prevents water from undesirably
staying in the vicinity of the relief valve.
[0013] In addition to the second feature, according to a third
feature of the present invention, at least a part of the relief
valve is housed inside the cover member.
[0014] With the third feature, at least a part of the relief valve
is housed inside the cover member, which forms the pressure
regulating passage by covering the upper portions of the first and
the second openings of the cooling water passage forming member.
Therefore, the cooling water passage forming member is made to be
compact and light compared to the case where the pressure
regulating passage and the relief valve are housed inside the
cooling water passage forming member.
[0015] As will be clear from the following discussion, a mount case
corresponds to the cooing water passage forming member of the
present invention, and a cylinder block cooling water jacket and a
cylinder head cooling water jacket correspond to the water jacket
of the present invention.
[0016] The above-mentioned aspects, characteristics, and advantages
of the present invention will become apparent from an explanation
of a preferred embodiment, which will be described in detail below
by reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a partial cross-sectional side view of an outboard
engine system according to an embodiment of the present
invention;
[0018] FIG. 2 is an enlarged cross-sectional view taken along line
2-2 in FIG. 1;
[0019] FIG. 3 is a view taken from the direction of arrow 3 in FIG.
2;
[0020] FIG. 4 is a view taken from the direction of arrow 4 in FIG.
3;
[0021] FIG. 5 is an enlarged cross-sectional view of an essential
part in FIG. 3;
[0022] FIG. 6 is a view taken from the arrows of line 6-6 in FIG.
5; and
[0023] FIG. 7 is a schematic diagram of the flow of cooling water
through an engine cooling system according to the embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] As shown in FIG. 1 and FIG. 2, an outboard engine system O
is mounted to a body of a boat to steer in a lateral direction
about a steering shaft 96, as well as to tilt in a vertical
direction about a tilt shaft 97. An in-line four-cylinder
four-stroke water-cooling vertical engine E is mounted on an upper
portion of the outboard engine system O and includes a cylinder
block 11; a lower block 12 connected to a front surface of the
cylinder block 11; a crankshaft 13, which is disposed generally
vertically and supported so that journals 13a are sandwiched
between the cylinder block 11 and the lower block 12; a crankcase
14 connected to a front surface of the lower block 12; a cylinder
head 15 connected to a rear surface of the cylinder block 11; and a
head cover 16 connected to a rear surface of the cylinder head 15.
Pistons 18 slidably fitted inside corresponding sleeve-shaped
cylinders 17, formed by enveloped-casting in the cylinder block 11,
are respectively connected to crank pins 13b of the crankshaft 13
via connecting rods 19.
[0025] Combustion chambers 20 formed in the cylinder head 15
opposite the top surfaces of the pistons 18 are connected to an
intake manifold 22 via intake ports 21 which are open to a left
side surface of the cylinder head 15, namely, a port side in a
traveling direction of the ship. The combustion chambers 20 are
also connected to an exhaust passage 24 inside an engine room via
exhaust ports 23 which are open to a right side surface of the
cylinder head 15. Intake valves 25 for opening and closing a
downstream end of the intake ports 21 and exhaust valves 26 for
opening and closing an upstream end of the exhaust ports 23 are
driven to open and close by a DOHC-type valve moving mechanism 27
housed inside the head cover 16. An upstream side of the intake
manifold 22 is disposed in front of the crankcase 14, connected to
a throttle valve 29 fixed to a front surface, and supplied with
intake air through a silencer 28. Injectors 58 for injecting a fuel
into the intake ports 21 are provided at an injector base 57
sandwiched between the cylinder head 15 and the intake manifold
22.
[0026] A chain cover 31 housing a timing chain (not shown) that
transmits a driving force of the crankshaft 13 to the valve moving
mechanism 27 is connected to upper portions of the cylinder block
11, the lower block 12, the crankcase 14, and the cylinder head 15
of the engine E. An oil pump body 34 is connected to lower surfaces
of the cylinder block 11, the lower block 12, and the crankcase 14.
A mount case 35, an oil case 36, an extension case 37, and a gear
case 38 are sequentially connected to a lower surface of the oil
pump body 34.
[0027] The oil pump body 34 houses an oil pump 33 between a lower
surface of the oil pump body 34 and an upper surface of the mount
case 35. On the opposite side, a flywheel 32 is disposed between
the oil pump body 34 and a lower surface of the cylinder block 11,
and the like. A flywheel chamber and an oil pump chamber are
defined by the oil pump body 34. The oil case 36, the mount case
35, and a periphery of a part of a lower side of the engine E are
covered with an undercover 39 made of a synthetic resin. An upper
part of the engine E is covered with an engine cover 40 made of a
synthetic resin connected to an upper surface of the undercover
39.
[0028] A drive shaft 41 connected to a lower end of the crankshaft
13 penetrates through the pump body 34, the mount case 35, and the
oil case 36, extends downward inside the extension case 37, and is
connected to a front end of a propeller shaft 44. The shaft 44
includes a propeller 43 at a rear end and is supported at a gear
case 38 in a longitudinal direction via a forward and reverse
travel switching mechanism 45 which is operated by a shift rod 52.
A lower water supply passage 48, which extends upward from a
strainer 47 provided at the gear case 38, is connected to a cooling
water pump 46 provided at the drive shaft 41. An upper water supply
pipe 49, which extends upward from the water cooling pump 46, is
connected to a cooling water supply passage 36b (see FIG. 7)
provided in the oil case 36.
[0029] Next, a structure of an exhaust system and a cooling system
of the engine E will be explained based on FIG. 2 to FIG. 7.
[0030] The exhaust passage means of the engine E is broadly divided
into an exhaust passage 24 portion in an engine room and an exhaust
chamber portion divided from the engine room. The exhaust passage
24 in the engine room includes: an exhaust manifold 61 including
single pipe portions 61a, which are connected to a right side
surface of the cylinder head 15 and introduce exhaust gas from each
of the combustion chambers 20; a collecting part 61b in which these
single pipe portions 61a are collected at the downstream regions of
the single pipe portions 61a; and an exhaust guide 62 for guiding
the exhaust gas to the outside of the engine room.
[0031] The exhaust guide 62 is connected to the upper surface of
the mount case 35 which forms a partition wall of the engine room
and communicates with an exhaust passage 35b penetrating through
the mount case 35. The exhaust passage 35b communicates with an
exhaust chamber 63 (see FIG. 7) in the extension case 37 via an
exhaust pipe portion 36c integrally formed with the oil case
36.
[0032] The exhaust manifold 61 includes a plurality, e.g., four,
single pipe portions 61a, communicating with a corresponding number
of exhaust ports 23, and the collecting part 61b where the single
pipe portions 61a are integrally collected. The collecting part 61b
extends in a direction away from the cylinder block 11 and is
disposed along the cylinder head 15 and the head cover 16. The
exhaust guide 62 is curved into an S-shape, and a lower end portion
of the exhaust manifold 61 is fitted to an inner periphery of a
connecting portion 62a having a large diameter at an upper end of
the exhaust guide 62.
[0033] A first exhaust guide cooling water jacket JM1, covering
half of the periphery of an upper surface side of the exhaust guide
62, and a second exhaust guide cooling water jacket JM3, covering
half of the periphery of a lower surface side of the exhaust guide
62, surround the exhaust passage 62d. An exhaust manifold cooling
water jacket JM2 surrounds a periphery of the exhaust manifold 61.
When the lower end of the exhaust manifold 61 is fitted to an inner
periphery of the connecting portion 62a of the exhaust guide 62,
the exhaust manifold cooling water jacket JM2 of the exhaust
manifold 61 and the first exhaust guide cooling water jacket JM1 of
the exhaust guide 62 communicate with each other.
[0034] The first exhaust guide cooling water jacket JM1
communicates with a cooling water supply hose 112 (described below)
via an unillustrated connecting hole 62e and a connecting hose, and
supplies and discharges the cooling water when the engine
stops.
[0035] As shown in FIG. 5 and FIG. 6, a first opening 35d and a
second opening 35e are formed adjacent to each other in an upper
wall 35c of the mount case 35. The first opening 35d communicates
with the exhaust chamber 63 via the oil case 36 from a cooling
water discharge passage 35f situated below the first opening 35d.
The second opening 35e communicates with the cooling water supply
passage 35a. The cooling water supply passage 35a and the cooling
water discharge passage 35f are partitioned by a partition wall
35g. A cover member 64 is fixed to the upper wall 35c of the mount
case 35 via a seal member 65 with two bolts 66 and 66 to cover the
first opening 35d and the second opening 35e. A pressure regulating
passage 64a, connecting the cooling water supply passage 35a and
the cooling water discharge passage 35f, is formed inside the cover
member 64.
[0036] The relief valve 51, disposed in the first opening 35d of
the upper wall 35c of the mount case 35 and the cover member 64,
includes a valve seat 68 supported by the first opening 35d,
wherein the valve seat 68 includes an annular flange portion 68a
mounted to the first opening 35d via a seal member 67, and a
cylindrical seat portion 68b protruding downward from the periphery
of the flange portion 68a. A plate-shaped valve body 69 seated from
below at a lower end of the seat portion 68b of the valve seat 68
includes a spring seat 70 passing through the first opening 35d to
protrude into the cover member 64. The valve body 69 is biased
upward to the valve seat 68 by an elastic force of a valve spring
71 disposed between an upper end of the spring seat 70 and an upper
surface of an outer periphery portion of the valve seat 68. The
second opening 35e is disposed at a side closer to a tilt shaft 97
(see FIG. 1) than the first opening 35d. Therefore, when the
outboard engine system O is tilted upward in the direction of the
arrow T in FIG. 5, the position of the first opening 35d is
displaced to be higher than the position of the second opening
35e.
[0037] As shown in FIG. 4, a cooling water supply hose 112
extending from a joint 111 provided at the cover 64 is connected to
a joint 113 at a lower end of a base member 108 of the oil filter
106. A cooling water discharge hose 115, extending from a joint 114
provided at an upper end of the base member 108, is connected to a
joint 116 provided at an intermediate portion of a discharge pipe
88.
[0038] Next, referring mainly to FIG. 7, showing the flow path of
the cooling water, a structure and an operation regarding cooling
of the entire engine E will be explained.
[0039] When the drive shaft 41 connected to the crankshaft 13 is
rotated by operation of the engine E, the cooling pump 46 provided
at the drive shaft 41 is operated to supply the cooling water,
which is drawn up through the strainer 47, to the cooling water
supply port 36a at a lower surface of the oil case 36 via the lower
water supply passage 48 and the upper water supply pipe 49. The
cooling water, which passes through the cooling water supply port
36a, flows into the cooling water supply passage 36b of the oil
case 36 and the cooling water supply passage 35a of the mount case
35. Part of the cooling water branching from the cooling water
supply passage 36b and the cooling water supply passage 35a is
supplied to the first exhaust guide cooling water jacket JM1 formed
in the exhaust guide 62 of the exhaust passage 24 in the engine
room and the exhaust manifold cooling water jacket JM2 formed in
the exhaust manifold 61. The exhaust gas, which is discharged from
the combustion chambers 20 of the cylinder head 15, is discharged
to the exhaust chamber 63 via the single pipe portions 61a and the
collecting portion 61b of the exhaust manifold 61, the exhaust
passage 62d of the exhaust guide 62, the exhaust passage 35b of the
mount case 35, and the exhaust pipe portion 36c of the oil case 36.
During this process, the exhaust passage 24 in the engine room,
which assumes a high temperature due to the exhaust gas, is cooled
by the cooling water flowing through the first exhaust guide
cooling water jacket JM1 and the exhaust manifold cooling water
jacket JM2.
[0040] The cooling water flowing upward through the first exhaust
guide cooling water jacket JM1 and the exhaust manifold cooling
water jacket JM2 assumes a raised temperature and is discharged
from the joints 61d and 61e provided at the upper end of the
exhaust manifold 61 through a pipe (not shown), or the like, into
the exhaust chamber 63.
[0041] Meanwhile, a part of the cooling water having a low
temperature, which is supplied to the cooling water supply passages
36b and 35a leading to the cooling water supply port 36a, flows
into a lower end of a cylinder block cooling water jacket JB via
two through-holes 11d and 11e opened to a cooling water supply
passage 11c at the lower end of the cylinder block 11. A part of
the cooling water having a low temperature, which is supplied into
the cooling water supply passages 36b and 35a, flows from the
cooling water supply passage 11c at the lower end of the cylinder
block 11 through two cooling water supply passages 11g and 11h into
a lower end of a cylinder head cooling water jacket JH.
[0042] During warming-up of the engine E, valves of a first
thermostat 85, connected to the upper end of the cylinder block
cooling water jacket JB, and a second thermostat 86, connected to
the upper end of the cylinder head cooling water jacket JH, are
closed. The cooling water in the cylinder block cooling water
jacket JB and the cylinder head cooling water jacket JH remains
without flowing, thus promoting warming-up of the engine E. In this
case, the cooling water pump 46 continues to rotate, but the
cooling water leaks from the periphery of the rubber impeller,
wherein the cooling water pump 46 is substantially in an idling
state.
[0043] When warming-up of the engine E is completed and the
temperature of the cooling water rises, the valves of the first and
the second thermostats 85 and 86 open, and the cooling water in the
cylinder block cooling water jacket JB and the cooling water in the
cylinder head cooling water jacket JH flow from a common joint 87a
of a thermostat cover 87, through an exhaust pipe 88 and the joint
62h of the exhaust guide 62, into the second exhaust guide cooling
water jacket JM3. The cooling water, which cools the exhaust guide
62 while flowing through the second exhaust guide cooling water
jacket JM3, passes downward through the mount case 35 and the oil
case 36 and is discharged into the exhaust chamber 63.
[0044] The cooling water, which branches into the cooling water
supply hose 112 from the joint 111 of the cover member 64 of the
relief valve 51, flows inside the water jacket of the base member
108 of the oil filter 106, and cooling water, which cools oil to
assume a raised temperature, is discharged into the intermediate
portion of the exhaust pipe 88 via the cooling water discharge hose
115.
[0045] When the rotational speed of the engine E increases, and the
water pressure of the cooling water supply passage 35a of the mount
case 35 is at a predetermined value or more, the water pressure
acts on the relief valve 51 provided at the first opening 35d via
the second opening 35e and the pressure regulating passage 64a of
the cover member 64, so that the valve body 69, which is pushed
down against the elastic force of the valve spring 71, is separated
from the valve seat 68 and the relief valve 51 opens. As a result,
as shown by the arrows A and B in FIG. 5, the cooling water, which
passes through the relief valve 51, is discharged into the exhaust
chamber 63 via the cooling water discharge passage 35f.
[0046] When the rotational speed of the engine E decreases, or when
the engine E stops, the water pressure of the cooling water supply
passage 35a becomes less than the predetermined value and the
relief valve 51 closes. When the engine E stops, the cooling water
pump 46 also stops and supply of the cooling water is not
performed. Therefore, the cooling water staying in the pressure
regulating passage 64a inside the cover member 64 flows down to the
cooling water supply passage 35a through the second opening 35e via
gravity, and is leaked through the gap of the impeller of the
cooling water pump 46 to be discharged. In this case, the cooling
water remaining in a recess surrounded by the valve seat 68 and the
valve body 69 of the relief valve 51 is leaked through the gaps
between the valve seat 68 and the valve body 69 little by little to
be discharged.
[0047] In addition, the valve seat 68 of the relief valve 51
includes the annular flange portion 68a mounted to the first
opening 35d, and the cylindrical seat portion 68b protruding
downward from an inner periphery of the flange portion 68a.
Therefore, a recessed portion is prevented from being formed
between the flange portion 68a and the seat portion 68b, wherein
the water is unable to remain.
[0048] On the other hand, in the conventional relief valve in which
the valve body is seated on the valve seat from above, the valve
seat protrudes upward to the valve body, which is seated from
above, and therefore, a recess is formed around the valve seat, and
the cooling water staying in the recessed portion is not able to be
discharged for a long time.
[0049] When the outboard engine system O is tilted upward about the
tilt shaft 97 (see FIG. 1) to land the outboard engine system O,
the relief valve 51 tilts upward in the direction of the arrow T in
FIG. 5. As a result, the position of the first opening 35d provided
with the relief valve 51 becomes higher than the position of the
second opening 35e, which is not provided with the relief valve 51,
and the cooling water staying in the upper portion of the relief
valve 51 is forcibly discharged from the pressure regulating
passage 64a inside the cover member 64 through the second opening
35e into the cooling water supply passage 35a, as shown by the
arrow C. If the relief valve 51 was provided in the second opening
35e, the cooling water of the pressure regulating passage 64a would
be moved to the side of the relief valve 51 by tilting the outboard
engine system O upward, that is, the cooling water would not be
prevented from staying.
[0050] The cover member 64 is fixed to the upper surface of the
mount case 35 with the bolts 66 and 66 to form the pressure
regulating passage 64a, and an upper half portion of the relief
valve 51 is housed therein, thus contributing to making the mount
case 35 compact and light as compared with the case where the
entire pressure regulating passage 64a and the relief valve 51 are
provided inside the mount case 35.
[0051] Although an embodiment of the present invention has been
described above, various changes in design can be made within the
scope of the present invention.
[0052] For example, the second feature of the invention is
applicable to an outboard engine system in which the cooling water
supply passage 35a is provided as a cooling water exhaust passage,
the cooling water discharge passage 35f is provided as a cooling
water supply passage, and the valve body 69 may be seated from
above the valve seat 68.
* * * * *